GB2036254A

GB2036254A - Controlled deflection rolls

Info

Publication number: GB2036254A
Application number: GB7939639A
Authority: GB
Original assignee: Escher Wyss AG
Current assignee: Sulzer Escher Wyss AG
Priority date: 1978-11-15
Filing date: 1979-11-15
Publication date: 1980-06-25
Also published as: ES485659A1; FI793502A; NL7907819A; US4291447A; JPS5569315A; BR7907394A; AR231333A1; SE7909364L; IT1124942B; AT367121B; FR2441756A1; IT7927156A0; CA1103485A; DE2850415C2; ATA830078A; JPS6325208B2; DE2850415B1

Description

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GB2 036 254A

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SPECIFICATION Controlled deflection rolls

5 This invention relates to a controlled deflection roll comprising a stationary beam and a roll shell which is rotatable about the beam and is mounted at each end on the beam in a bearing, at least one support element being 10 provided between the beam and the roll shell for rotatably supporting the shell on the beam, the force of the support element or elements acting in a direction extending along a pressure plane passing through the axis of 15 the shell.

A controlled deflection roll of this construction is described in, for example. United States Patent Specification No. 3 802 044. In this well-proven controlled deflection roll, the 20 support elements are in the form of pistons or plungers which are subjected to hydrostatic biasing forces and which also provide hydrostatic bearings by which they bear against the inner surface of the shell. The 25 pistons may all be subjected to the same hydrostatic pressure or may be subjected to different pressures in groups or individually.

It has been found that when a controlled deflection roll of this construction is installed 30 in a roll stand there is a risk of the roll shell breaking if the hydrostatic support elements are subjected to pressure in the absence of a counter roll or if the surface of the counter roll is too far away from the roll shell. This may 35 occur, for example, if the shells of a roll stand are reground.

According to the present invention, a controlled deflection roll comprises a stationary beam and a roll shell which is rotatable about 40 the beam and is mounted at each end on the beam in a bearing, at least one support element being provided between the beam and the roll shell for rotatably supporting the shell on the beam, the force of the support element 45 or elements acting in a direction extending along a pressure plane passing through the axis of the shell, each of the bearings having, in the pressure plane and on the rear side of the shell axis when considered in the direction 50 of the force, a clearance which allows the bearing to move with respect to the beam from an operative position in the opposite direction to the direction of the force, means for providing a yielding force to hold the ! 55 bearing in the operative position on the beam, and a control means responsive to movement of the bearing out of the operative position on the beam in opposition to the force of the force providing means to limit the force of the 60 support element or elements.

The force providing means holds the bearing in the operative position up to a given support element force which is safe for the roll shell. As soon as that force is exceeded, 65 the force of the force providing means is overcome and the bearing is moved out of the operative position, so that the control means is actuated. The control means then limits the support element force to a value which is safe 70 for the shell, e.g. by limiting the pressure of the hydraulic pressure fluid fed to the support element.

The force providing means may take various forms; for example, it may comprise a spring 75 of adequate size. Preferably, however, the force providing means is a hydraulic pressure chamber provided between the bearing and the beam and connected to means arranged to supply hydraulic pressure fluid at a pres-80 sure determined by a pressure controller.

Apart from the fact that a hydraulic pressure chamber can develop much greater forces than a spring, it is possible to adjust the required force from outside by means of the 85 pressure controller.

The control means may, for example, be an electrical limit switch. Preferably, however, the control means is a hydraulic valve means which, when the bearing moves out of the 90 operative position in the opposite direction to the direction of the force of the supporting element, opens a flow path from the pressure line to which it is connected.

In a particularly advantageous embodiment, 95 the valve means may be formed by a surface of the bearing, the said surface, in the operative position, shutting off the orifice of a bore in the beam, such bore leading to the said surface. A construction of this kind has the 100 advantage of great simplicity and yet is operative on the smallest movement of the bearing away from the beam.

To increase the efficiency, the valve means may include a valve control means which is 105 movable in sealing-tight relationship in the bore, the valve control member shutting off an exit port branching from the bore and being actuated by the first valve means by servo action. In this way, a large flow cross-110 section can be opened by the valve control member with the minimum lifting movement.

Preferably, the pressure chamber forming the force providing means is formed by a gap between the beam and the bearing. This gives 115a pressue chamber with the maximum operative cross-section using minimal means, simply by providing a seal. This may be achieved in two ways. Firstly, the beam may have a cylindrical outer surface at the bearing, the 120 bearing including a ring which bears on the cylindrical outer surface and which has an oval bore with two surfaces which are offset from one another by an amount equal to the size of the gap. This construction is readily 125 manufactured because the beam journal is cylindrical and the oval opening is confined to a ring of the bearing.

Alternatively, the beam at the bearing has an outer surface consisting of two cylindrical 130 surfaces which have the same radii and whose

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axes are offset from one another by an amount equal to the thickness of the gap, and the bearing has a cylindrical surface surrounding the said surfaces. In this case, although it 5 is rather more complicated to form the outer surface of journal on the beam, the ring may in some cases be formed by the inner ring of the rolling bearing provided at that point.

The invention may be carried into practice 10 in various ways but one controlled deflection roll embodying the invention and two possible modifications will now be described by way of example with reference to the accompanying diagrammatic drawings, in which:

15 Figure 7 is a diagrammatic detail of a rolling system with the roll according to the invention, a counter roll and the hydraulic circuit for the roll;

Figure 2 is a partial section of the roll of 20 Fig. 1 to an enlarged scale;

Figure 3 is a section on Ill-Ill in Fig. 1;

Figure 4 is a detail of Fig. 2 to an enlarged scale;

Figure 5 shows the journal of the beam 25 with a cylindrical surface and an oval bearing surface with a clearance between them;

Figure 6 shows a modification in which the journal of the beam has an oval surface and the bearing has a cylindrical surface; and 30 Figure 7 is a detail of Fig. 1 with a modification in which the throttle is replaced by a pressure control valve.

Fig. 1 shows a controlled deflection roll comprising a stationary beam 1 and a shell 2 35 rotatable about the beam. As already stated, the roll can be constructed generally in the manner described in United States Patent Specification No. 3 802044, in which the inner surface of the shell is mounted 40 hydrostatically on support elements in the form of pistons which are themselves hydrostatically supported in the beam. Such support elements could be replaced by other support elements such as support elements on 45 which the roll shell is borne hydrodynamically.

As will also be seen from Fig. 1, the ends of the beam 1 are carried in columns 3,

which are shown only diagrammatically. The shell 2 co-operates with a counter roll 4, 50 which may be provided with a biasing system (not shown) to provide a biasing force. As, for example, in a calender, the roll stand may comprise more than two rolls of which only the upper or lower may have a biasing sys-55 tem. It may be an external biasing system, e.g. with cylinders, or alternatively a controlled deflection roll may be used which is itself adapted to provide the biasing force, as described in United States Patent Specifica-60 tion No. 3 885 283.

As will be seen from Fig. 2, each end of the roll shell 2 is mounted on the beam 1 in rolling bearings 5. An intermediate ring 7 is provided between the inner ring of the rolling 65 bearing 5 and an outer surface 6 of the beam

1. The outer end of the shell 2 is sealed off by a cover 8. Hydrostatic support pistons 11 of the construction described in United States Patent Specification No. 3 802 044 are pro-70 vided in sealing-tight relationship in bores 10 in the beam 1. The bores 10 are connected by connecting bores 12' to a common distribution bore 12, which is in turn connected to an external feed conduit 1 3 for hydraulic 75 pressure fluid (Fig. 1).

A diametral bore 14 is formed in the beam 1 and has a larger-diameter portion 14' at one end. A step which forms a valve seat 1 5 is provided between the wider and narrower 80 portions of the bore 14. Above the valve seat 15, the bore 14' is surrounded by a groove 16 from which an inclined bore 1 7 leads into the space 18 between the beam 1 and the shell 2. The bore 14 is connected via a bore 85 20 to a conduit 21 for hydraulic pressure fluid.

As will be seen from Fig. 4, a valve member 22 is guided with little clearance in the bore 14'. In the position illustrated, the valve 90 member 22 is pressed against the valve seat 1 5 by a spring 23 and thus shuts off the bore 14. Its outer surface 24 in this position also shuts off the groove 16 and hence the connection between the bore 14 and the bore 95 17. One end of the spring 23 abuts the inner surface 25 of the intermediate ring 7 which, in the position illustrated, also shuts off the mouth 26 of the bore 14'. This mouth, which together with the surface 25 also forms a 100 valve, as will be apparent from the following description, is surrounded by an annular groove 27, from which a straight groove 28 leads to the outer end surface of the ring 7. As can be seen in Fig. 4, the valve member 105 22 is also provided with a throttle bore 30 which interconnects its two ends and hence also the portions of the bore 14. As will also be apparent from Fig. 2, there is a gap 19 between the beam and the intermediate ring 110 7 on the beam side remote from the larger diameter portion 14' of the bore 14. as can be seen from Fig. 5, this gap results from the fact that the beam 1 has a cylindrical outer surface 31 of diameter D and axis A at the 115 place where it is mounted by means of the rolling bearing 5 and the intermediate ring 7 while the bore of the intermediate ring 7, on the other hand, consists of two part-cylindrical surfaces 25 and 25' with respective axes A 120 and A', which are offset by an amount S in the pressure plane E along which the direction K of the force of the support elements 11 extends. The diameters of the two surfaces 25 and 25' are equal and equivalent to the 125 outside diameter D of the journal of the beam 1. As will be seen from Fig. 5, the offset S of the axes A and A' of the surfaces 25 and 25' determines the size of the gap 19. In principle this may be very small and, for example, be 130 just a few tenths of a millimetre.

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As will also be apparent from Figs. 2 and 3, the surfaces 25, 25' are surrounded by seals 40 and 41 so that the gap 1 9 between the surfaces 25' and 31 forms a pressure cham-5 ber connected to the bore 14.

As will be seen from Fig. 1, the controlled deflection roll is connected to a hydraulic pressure fluid source 50 containing a pump 51. The source 50 has a pressure control 10 valve 52 which determines the pressure in the line 21 and hence the pressure operative in the gap 19. The line 13 contains a pressure control valve 53, by means of which it is possible to adjust the force with which the 15 shell 2 is borne in opposition to the force of the counter roll 4. The pressure line 21 leads to the bore 20 and hence also to the bore 14 and the gap 19 at the end of the beam 1 in the shell mounting 5, 7. The pressure in the 20 line 21 under the influence of the pressure control valve 53, together with the equivalent area of the surface on which the pressure in the gap 19 is operative, determines the force with which the surfaces 25 and 31 (Fig. 5) 25 are pressed against one another, the orifice 26 of the bore 14' being kept closed by the surface 25.

A throttle 54 is also provided in the line 21, as will be seen from Fig. 1.

30 During normal operation of the roll, the force of the pressure elements 11 is so selected that this force is substantially balanced by the biasing force of the counter roll 4, so that the bearings 5 at the two ends of the roll 35 are relieved of load and have substantially no loading to take. The hydraulic force operative in the gap 1 9 presses the surfaces 25 and 31 against one another in these conditions so that the orifice 26 of the bore 14' remains 40 closed. If, however, the force of the support elements 11 comes into operation in the direction K (Fig. 5) without, for some reason, a counter roll 4 taking this force by a counteracting force, the bearings 5 are subjected to a 45 corresponding loading. If, in such circumstances, the forces exerted by the support elements were to become very large, the roll shell 2 could break. However, in the roll being described, this is prevented. When the force

50 of the support elements reaches a certain

and still safe— value, the hydraulic force operative in the gap 19 as defined by the pressure controller 52 is overcome, so that the beam 1 is moved downwardly with re-' 55 spect to Fig. 2, i.e. in opposition to the direction of the force K, in the oval bore 25, 25' of the intermediate ring 7.

In these conditions the surface 25 of the intermediate ring 7 is lifted away from the 60 orifice 26 of the bore 14', so that the pressure fluid therein can flow off through the grooves 27 and 28. Since the throttle bore 30 prevents rapid replacement of the pressure fluid, the pressure in the bore portion 14' is 65 reduced, so that the valve member 22 moves upwards with respect to Fig. 4, The annular groove 16 is thus opened, with the result that the bore 14 communicates with the bore 17. The throttle 54 prevents any reduction of the 70 pressure below a required value in line 13 and in that part of the line 21 which precedes the throttle. The reason for this is that in many cases it is desirable that the force of the support elements 11 should not drop below a 75 minimum safe value for the roll shell so that, for example, the support elements are always able to take the deadweight of the shell 2.

Fig. 6 shows another possible construction of the gap 19 between the beam 1 and the 80 mounting of the shell 2. In this case, the ring surrounding the beam has 3 cylindrical bore with a surface 25 of diameter D. The outer surface of the beam 1 at the place of the mounting is oval, being formed by two sur-85 faces 31 and 31'. Although these are each of the same diameter D, their axes A and A" are offset from one another by the amount S. Unlike the construction shown in Fig. 4, in which the offset of the axes A and A' is such 90 as to increase the size of the bore in the direction of the plane E, the offset in this case results in a reduction of the outer dimension of the surface of the beam.

Fig. 7 shows a modification in which the 95 throttle 54 is replaced by a pressure control valve 54'. When the beam falls and the valve member 22 moves to open the passage 17, the pressure control valve 54' allows a flow from the upstream part of the line 21 only to 100 an extent such as to maintain the required lower pressure in that part of the line.

Although Fig. 1 shows only a single pressure line 1 3 for reasons of simplicity, a larger number of such lines with corresponding con-105 trailers 53 may be provided, for example in order to feed a plurality of pressure zones along the roll with different pressures. As already stated, the support elements may be constructed in any desired manner and the 110 invention is not restricted to a hydraulic construction of such support elements.

Claims

1. A controlled deflection roll comprising a 115 stationary beam and a roll shell which is rotatable about the beam and is mounted at each end on the beam in a bearing, at least one support element being provided between the beam and the roll shell for rotatably 120 supporting the shell on the beam, the force of the support element or elements acting in a direction extending along a pressure plane passing through the axis of the shell, each of the bearings having, in the pressure plane and 125 on the rear side of the shell axis when considered in the direction of the force, a clearance which allows the bearing to move with respect to the beam from an operative position in the opposite direction to the direction of the force, 1 30 means for providing a yielding force to hold

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the bearing in the operative position on the beam, and a control means responsive to movement of the bearing out of the operative position on the beam in opposition to the 5 force of the force providing means to limit the force of the support element or elements.

2. A roll as claimed in Claim 1 in which the force providing means is a hydraulic pressure chamber provided between the bearing

10 and the beam and connected to means arranged to supply hydraulic pressure fluid at a pressure determined by a pressure controller.

3. A roll as claimed in Claim 2 in which the control means is a hydraulic valve means

15 which, when the bearing moves out of the operative position in the opposite direction to the direction of the force of the supporting element, opens a flow path from the pressure line to which it is connected.

20 4. A roll as claimed in Claim 3 in which the valve means is formed by a surface of the bearing, the said surface, in the operative position, shutting off the orifice of a bore in the beam leading to the said surface.

25 5. A roll as claimed in Claim 4 in which the valve means includes a valve control member which is movable in sealing-tight relationship in the bore, the valve control member shutting off an exit port branching

30 from the bore and being actuated by the first valve means by servo action.

6. A roll as claimed in any of Claims 2 to 5 in which the pressure chamber is formed by a gap between the beam and the bearing.

35 7. A roll as claimed in Claim 6 in which the beam has a cylindrical outer surface at the bearing and the bearing includes a ring which bears on the cylindrical outer surface and which has an oval bore with two surfaces

40 which are offset from one another by an amount equal to the size of the gap.

8. A roll as claimed in Claim 6 in which the beam at the bearing has an outer surface consisting of two cylindrical surfaces which

45 have the same radii and whose axes are offset from one another by an amount equal to the thickness of the gap and the bearing has a cylindrical surface surrounding the said surfaces.

50 9. A controlled deflection roll substantially as described herein with reference to Figs. 1 to 5 of the accompanying drawings.

10. A roll as claimed in Claim 9 modified substantially as described in Fig. 6 or Fig. 7 of the accompanying drawings.

Printed for Her Majesty's Stationery Office by Burgess & Son (Abingdon) Ltd.—1980.

Published at The Patent Office, 25 Southampton Buildings,

London, WC2A 1AY, from which copies may be obtained.